I have not bothered with
I have not bothered with running slides on my plasma nor do I recommend it in general. The only time I think there is some merit to running slides is if you need to rapidly overcome the initial aging process of the plasma cells so that a pro calibration can be performed allowing the results to be more accurate over time. Otherwise, the cells will age as you watch content. If plasma technology were as sensitive as you fear, manufacturers would have long ago stopped selling them due to all the returns they would suffer. I have run the desktop on a screen for 30 minutes to an hour with no consequence many times on my plasmas.
To have both HD audio and HDMI 1.4 in your case, you should be able to feed one output to your display and another output to your receiver. Your card may require a DVI to HDMI adapter if it only has a single HDMI output.